add device-specific hooks at start of OTA phases

Change-Id: I47534e6d40e7918ee8cb9e87d76d9030b9273708
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
index 1514ea7..f05cd1b 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files
@@ -382,6 +382,7 @@
 
   AppendAssertions(script, input_zip)
   device_specific.FullOTA_Assertions()
+  device_specific.FullOTA_InstallBegin()
 
   script.ShowProgress(0.5, 0)
 
@@ -559,6 +560,8 @@
 
   script.Print("Verifying current system...")
 
+  device_specific.IncrementalOTA_VerifyBegin()
+
   script.ShowProgress(0.1, 0)
   total_verify_size = float(sum([i[2].size for i in patch_list]) + 1)
   if updating_boot:
@@ -594,6 +597,8 @@
 
   script.Comment("---- start making changes here ----")
 
+  device_specific.IncrementalOTA_InstallBegin()
+
   if OPTIONS.wipe_user_data:
     script.Print("Erasing user data...")
     script.FormatPartition("/data")